Introduction/Background Few studies to date have comprehensively examined all immune-related adverse events (irAEs) in vulvovaginal and cutaneous melanoma patients on immune checkpoint inhibitors (ICIs).

Methodology We retrospectively analyzed 169 patients with advanced-stage vulvovaginal or cutaneous melanoma who received at least one dose of ICI between June 2012 to December 2018. Descriptive statistics were used to summarize the baseline characteristics, disease outcomes, and toxicity profiles. Chi-square statistical analysis was used to examine associations between irAEs and pre-existing conditions, as well as irAEs and treatment response. P-values <0.05 were considered statistically significant.

Results Overall, 53.8% of patients with vulvovaginal melanoma developed irAEs, compared to a similar percentage of 51.9% for patients with cutaneous melanoma. Yet the most common types of irAEs differed between patients. The most common irAEs for patients with vulvovaginal melanoma were gastrointestinal disorders (44.4%), hypothyroidism (22.2%), and renal and urinary disorders (22.2%). On the other hand, the most common irAEs for patients with cutaneous melanoma on ICIs were gastrointestinal disorders (21.7%), cutaneous adverse events (17.9%) and pneumonitis (18.75%). Cutaneous adverse events were overall the most common irAEs, and were significantly associated with patient response to ICIs (p = 0.01).

Conclusion Nuanced differences in the clinical presentation of irAEs in patients with vulvovaginal vs. cutaneous melanoma are important considerations for initiating ICIs in accordance with melanoma type. Furthermore, cutaneous adverse events were the most common irAEs overall, and were significantly associated with response to ICIs in patients with metastatic melanoma.

Disclosures I have no conflicts of interest.